镁对在体兔缺血—再灌心脏的电生理效应

本实验通过结扎兔冠状动脉左室支复制动脉缺血－再灌注模型，应用心外膜接触电极记录单相动作电位，观察后除极电位在再灌注性心律失常中及镁离子的拮抗作用。结果表明，再灌性心律失常的５２．６％与早期后去极化有关。硫酸镁可终止及预防ＲＡ，对再灌中出现触发活动有抑制作用。     

Comparison of different PCR approaches for characterization of Burkholderia (Pseudomonas) cepacia isolates.

In this study, we evaluated three PCR methods for epidemiological typing of Burkholderia (Pseudomonas) cepacia--PCR-ribotyping, arbitrarily primed PCR (AP-PCR) and enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR)--and compared them with pulsed-field gel electrophoresis. The analysis was performed with 31 isolates of B. cepacia, comprising 23 epidemiologically unrelated isolates and 8 isolates collected from the same patient during two episodes of bacteremia. Pulsed-field gel electrophoresis, ERIC-PCR, and AP-PCR identified 23 distinct types among the 23 unrelated isolates, while PCR-ribotyping only identified 12 strain types, even after AluI digestion of the amplification products. Among the eight isolates collected from the same patient, all typing techniques revealed two clones of strains. The day-to-day reproducibilities of PCR-ribotyping and ERIC-PCR were good, while greater day-to-day variations were noted in the fingerprints obtained by AP-PCR. We conclude that all three PCR techniques are useful for rapid epidemiological typing of B. cepacia, but ERIC-PCR seems to be more reproducible and discriminative.     

Alpha-methylacyl-CoA racemase/P504S overexpression in colorectal carcinoma is correlated with tumor differentiation.

Alpha-methylacyl-CoA racemase (AMACR)/P504S is an enzyme involved in the metabolism of branched-chain fatty acids. Little is known about correlation of AMACR expression with colorectal carcinoma (CRC) differentiation and prognosis. We investigated the expression of AMACR in 106 cases of primary CRC, and in 47 lymph nodes with metastatic CRC by immunohistochemical analysis. These cases were divided into 3 groups according to the histologic differentiation of the primary tumors. group A included 50 cases of histologically well and moderately differentiated CRCs, 20 of these with lymph node metastasis; group B included 23 cases of well and moderately differentiated CRCs, histologically similar to group A, except these tumors had small foci (less than 20%) of high-grade carcinoma, and 10 of these had lymph node metastasis; group C included 33 cases of poorly differentiated adenocarcinoma and undifferentiated carcinoma, 17 with lymph node metastasis. The results showed the overall positive rates of expression in primary and metastatic CRCs were 59.4% and 46.8%, respectively. Expression in groups A (76.0%) and B (69.6%) was much higher than that in group C (27.3%). In group B, although overexpression of AMACR in primary tumors was similar to that of group A, it was only seen in 30.0% of group B metastatic tumors, which was similar to the rate of expression in group C (23.5%). In contrast, rates of expression in group A primary and metastatic tumors were similar (80.0% and 75.0%). Positive staining for AMACR in benign epithelium adjacent to tumor was rare (<2%). No relation was found between AMACR expression and overall survival. Our findings support the view that the expression of AMACR in CRC is correlated with tumor differentiation.     

日本血吸虫大陆株26kDa谷胱甘肽S┐转移酶编码区基因的克隆及序列测定

从日本血吸虫大陆株成虫分离总ＲＮＡ，逆转录合成ｃＤＮＡ第一链，根据菲律宾株２６ｋＤａ谷胱甘肽Ｓ－转移酶（ＧＳＴ）的ｃＤＮＡ序列，设计并合成引物，扩增出２６ｋＤａ的编码区基因，并克隆到ｐＢｌｕｅｓｃｒｉｐｔ质粒。初步酶切鉴定后，从两端对插入片段进行核苷酸序列测定。结果与菲律宾株比较，核苷酸同源性为９９．８％，仅第５８２位碱基不同，菲律宾株为Ａ，而大陆株为Ｇ。比较从ｃＤＮＡ推导出的氨基酸序列，两者１００％相同。测序结果也与曼氏血吸虫进行了比较。     

A novel configuration of bioartificial liver support system based on circulating microcarrier culture

The purpose of this investigation is to initiate a new bioartificial liver support system that utilizes circulating microcarrier cultures in the extracapillary space of a hollow fiber cartridge. The material exchange occurs on the membranes of the hollow fiber. Toxins are metabolized by the circulating cells on the microcarriers driven by a centrifugal pump. We inoculated 2-3 x 10E8 Hep G2 cells on 2.5 grams of Cytodex 3 microcarriers, and allowed them flowing in the extracapillary space of a modified plasma filter. 10% FCS Medium was pumped through the capillaries at different rates. Cells keep morphological integrity and functionality during the circulation. These preliminary results suggest that this configuration of a bioartificial liver support system offers a future investigation.     

Association of the CTLA-4 gene with rheumatoid arthritis in Chinese Han population

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is important for downregulation of T-cell activation, and CTLA-4 gene polymorphisms have been implicated as risk factors for rheumatoid arthritis (RA). Previous studies of the association between the +49 polymorphism of the CTLA-4 gene in RA have provided conflicting results. In order to determine association of the CTLA-4 gene with RA in Chinese Han population, we used denaturing gradient gel electrophoresis (DGGE) to genotype polymorphisms of four SNPs (MH30, +49, CT60 and JO31) of the CTLA-4 gene in 326 RA patients and 250 healthy controls. Furthermore, meta-analysis of all available studies relating +49 polymorphism to the risk of RA was performed to confirm the disease association. Among the SNPs examined, the genotype frequencies of CTLA-4 +49 and CT60 in RA patients differed significantly from controls (P=0.028 and 0.007). In addition, the distribution of four haplotypes constructed by these two SNPs was significantly different between patients and controls (chi(2)=10.58, d.f. =3, P=0.014). The meta-analysis also revealed that in both European and Asian populations, the CLTA-4 +49 G allele was associated with the risk of RA. These results suggested that the CTLA-4 gene might be involved in the susceptibility to RA in the Chinese Han population and both +49 and CT60 of CTLA-4 gene might be the causal variants in RA disease.     

Lysosome is a primary organelle in B cell receptor-mediated apoptosis: an indispensable role of Syk in lysosomal function

To investigate the mechanism of B cell receptor (BCR)-mediated apoptosis, we utilized immature B cell lines, DT40 and WEHI-231. In both cell lines, BCR-crosslinking caused the increase in lysosomal pH with early apoptotic changes characterized by chromatin condensation and phosphatidylserine exposure. This increase was detected in c-Abl-deficient DT40 cells but not in Syk-deficient cells, which corresponded to the fact that the former cells but not the latter revealed BCR-induced apoptosis. In contrast, BCR-crosslinking caused no apparent change in mitochondrial transmembrane potential. Therefore, the lysosomal change might be a primary event in BCR-induced apoptosis in DT40 cells. The increased activity of cathepsin B and apoptosis-preventing effect of a cathepsin inhibitor suggested a significant role of lysosomal enzymes in this apoptosis. By microscopic studies, lysosomes of wild-type DT40 cells fused to BCR-carrying endosomes became enlarged and accumulated one another. In contrast, these changes of lysosomal dynamics did not occur in Syk-deficient cells but transfer of wild-type Syk restored the lysosomal changes and apoptosis. These results demonstrated that the lysosomal change accompanied with the activation of lysosomal enzymes is a primary step in BCR-crosslinking-mediated apoptosis and Syk is responsible for this step through the fusion of BCR-carrying endosomes to lysosomes.     

Reduced p21(WAF1/CIP1) expression is an early event in gallbladder carcinogenesis and is of prognostic significance for patients with carcinomas of the gallbladder

The molecular basis underlying the development and progression of gallbladder carcinoma (GBC) remains poorly understood. To evaluate the roles of p21(WAF1/CIP1) and p53 in gallbladder carcinogenesis and to assess their prognostic significance for patients with GBC, we used immunohistochemistry to examine the expression of p21(WAF1/CIP1) and p53 protein in a series of surgically resected specimens, including normal epithelia, precancerous lesions adenoma, and dysplasia, and carcinomas of the gallbladder. Reduced p21(WAF1/CIP1) expression was frequently observed in carcinomas (18 of 37 lesions; 49%), and even in precancerous lesions adenomas (3 of 7; 43%) and dysplasias (5 of 5; 100%). p53 overexpression was detected in 43% of the adenomas, 60% of the dysplasias and 57% of the carcinomas. There was an inverse relationship between p21(WAF1/CIP1) and p53 expression in GBCs (P =.01). Survival analysis indicated that reduced p21(WAF1/CIP1) expression was significantly associated with shortened disease-free and overall survival (P =.04 and.03, respectively) for patients with stages II to IV GBCs. These observations suggest that reduced p21(WAF1/CIP1) expression and p53 overexpression contribute to GBC from an early stage and that determination of p21(WAF1/CIP1) expression in surgically resected specimens would add prognostic information to conventional pathologic examinations for patients with advanced-stage GBC.     

Toosendanin induces outgrowth of neuronal processes and apoptosis in PC12 cells

In the present study, the effects of toosendanin on cell differentiation and apoptosis were investigated in PC12 cells. The results showed that after 24-48 h of culture in a medium containing toosendanin (approximately 1-10x10(-7) M), cell differentiation and outgrowth of neuronal processes were promoted. Combined treatment with toosendanin and a calcium channel blocker, nifedipine or omega-conotoxin GVIA, resulted in a significant inhibition of the toosendanin-induced effects. Pretreatment of PC12 cells with BAPTA-AM also inhibited the toosendanin-induced effects; however, these effects were not inhibited by pertussis toxin and H-7 in the medium. Toosendanin also induced cell apoptosis. Based on the DNA content determined by flow cytometric analysis, the number of apoptotic cells significantly increased when the incubation time in the toosendanin-containing medium was lasted up to 72 h. Toosendanin at a higher concentration (> or =1 x 10(-6) M) caused cell death while it had no effect on cell division at concentrations lower than 1 x 10(-7) M.